Field
Embodiments described herein generally relate to an electrostatic chuck (ESC). More specifically, embodiments described herein relate to an improved electrostatic carrier design for thin substrate handling.
Description of the Related Art
In the processing of substrates, such as semiconducting substrates and displays, the substrate is held on a support in a process chamber during processing. The support can include an ESC that has an electrode capable of being electrically biased to hold the substrate on the support. The support can comprise a pedestal that supports the ESC in the chamber, and may be capable of raising or lowering the height of the ESC and substrate. The pedestal can also provide a protective enclosure for connecting wires, gas tubes, etc., that connect to portions of the support.
In some plasma processes used to process the substrate, energized gases are used to process the substrate by, for example, etching or depositing material on the substrate, or to clean surfaces in the chamber. These energized gases can comprise highly corrosive species, such as chemical etchants, as well as energized ionic and radical species that can erode portions of the ESC. The eroded ESC can be problematic because the damaged ESC may not provide the desired electrical characteristics for processing substrate or holding substrates. Also, particles that have eroded from the ESC can contaminate substrates being processes within the chamber.
ESC's made of ceramics may be desirable because they have improved resistance to corrosion by energized process gases, and can maintain their structural integrity even at high substrate processing temperatures exceeding several hundred degrees centigrade. However, a problem with conventional supports with integrated ESC's is that thermal expansion mismatch can occur between the ceramic ESC and the supporting pedestal, especially during substrate processes performed at high temperatures. The difference in thermal expansion coefficients of ceramic material and the metal pedestal can result in thermal and mechanical stresses that can cause the ceramic to fracture or chip.
Moreover, ceramic ESC's having multiple holes formed therethrough may be especially susceptible to cracking. Holes for vias used to couple electrodes within the ESC to a power source may be one example of a stress point which may induce cracking or fracturing of the ceramic material. The holes are generally considered inherent weak points in the mechanical integrity of the ESC. When an ESC is cracked or fractured, it may lose the ability to effectively retain a substrate and particle generation may be increased. In addition, the need to constantly replace cracked ESC's may be expensive and wasteful.
Thus, what is needed in the art is an ESC having improved mechanical integrity and reduced or eliminated stress initiation points while being able to maintain desirable electrostatic coupling characteristics.